Such an actuating drive for a rail guide is known from WO 03/068551 A1, U.S. Pat. Nos. 5,924,668 A, 5,860,319 A and 6,260,922 B1. Associated rail guides are known from DE 10 2006 048 786 A1, U.S. Pat. No. 5,941,495 A and DE 42 38 486 A1 (here, for example, FIG. 2), and from DE 10 2006 047 525 A1.
The spindles in the actuating drives according to the prior art extend in a straight line. This has great advantages; the spindles can be manufactured and, if necessary, aligned with precision, attachments are simple and a consistently good adjustability over the entire length of the adjustment distance can be obtained.
In the case of straight spindles, there is, however, the disadvantage that the seat is only moved in a linear manner in space when adjusted, but that no other movements are possible. A tall passenger will set the seat low in a downward direction and far backwards. In contrast, a small passenger will set the seat far towards the front and high. In the case of an adjustment mechanism according to the prior art, the inclination of the backrest is maintained. It can be set separately by means of a separate backrest joint. As a rule, a tall passenger will set the backrest into a position in which it is inclined more relative to the vertical than is the case for a small passenger. If a separate backrest joint is provided, this means a certain expenditure. The inclination of the seat surface is also chosen differently by tall and small persons. In order to be able to adjust the inclination of the seat surface, there are seat inclination adjustment mechanisms. They offer good comfort but also require added expenditure. In addition, the seats according to the prior art frequently have a seat height adjustment mechanism. This also means additional weight and additional expenditure. This applies to every additional adjustment device.